A long-term observational study of paediatric snakebite in Kilifi County, south-east Kenya

Dermonecrosis caused by a spitting cobra snakebite results from toxin potentiation and is prevented by the repurposed drug varespladib

Snakebite envenoming is a neglected tropical disease that causes substantial mortality and morbidity globally. The venom of African spitting cobras often causes permanent injury via tissue-destructive dermonecrosis at the bite site, which is ineffectively treated by current antivenoms. To address this therapeutic gap, we identified the etiological venom toxins in Naja nigricollis venom responsible for causing local dermonecrosis. While cytotoxic three-finger toxins were primarily responsible for causing spitting cobra cytotoxicity in cultured keratinocytes, their potentiation by phospholipases A2 toxins was essential to cause dermonecrosis in vivo. This evidence of probable toxin synergism suggests that a single toxin-family inhibiting drug could prevent local envenoming. We show that local injection with the repurposed phospholipase A2-inhibiting drug varespladib significantly prevents local tissue damage caused by several spitting cobra venoms in murine models of envenoming. Our findings therefore provide a therapeutic strategy that may effectively prevent life-changing morbidity caused by snakebite in rural Africa.

First aid and pre-hospital practices in snakebite victims: The persistent use of harmful interventions

First aid intervention and pre-hospital (FAPH) practices are common in patients suffering from snakebite envenomation (SBE). In this study, we have reviewed the literature concerning the use of these practices in various regions of the world in the period 1947-2023 based on published prospective studies. A total of 71 publications fulfilled the inclusion criteria. In terms of the total number of patients in all studies that used each FAPH intervention, the most common practice was the application of tourniquets (45.8%). Other FAPH practices described include cuts/incisions (6.7%), the application of a variety of natural or synthetic substances at the bite site (5.6%), and ingestion of natural, usually herbal, remedies (2.9%). Washing the site of the bite was described in 9.1% of patients. There were other less frequent FAPH practices, including suction, splinting-immobilization, pressure-bandage, ice packs, application of a snake/black stone, and administration of alcoholic beverages. There were differences in the extent of application of FAPH interventions in different continents. Tourniquets were highest (55.7%) in Asia. Topical application of various products was common in South America, while pressure-bandage was only reported in Australia. We did not find any statistically significant variations in the frequency of the most frequent FAPH interventions at three-time intervals (before 2006, between 2006 and 2015, and after 2015). Our findings highlight the use of FAPH interventions in patients suffering SBE, some of which are known to be harmful. It is necessary to study these practices to a higher level of geographic granularity, using community-based surveys. Programs tailored to local contexts should be promoted, aimed at avoiding the use of harmful FAPH practices. It is also necessary to assess the efficacy and safety of some interventions through robust preclinical and clinical studies.

Repurposed drugs and their combinations prevent morbidity-inducing dermonecrosis caused by diverse cytotoxic snake venoms

Morbidity from snakebite envenoming affects approximately 400,000 people annually. Tissue damage at the bite-site often leaves victims with catastrophic life-long injuries and is largely untreatable by current antivenoms. Repurposed small molecule drugs that inhibit specific snake venom toxins show considerable promise for tackling this neglected tropical disease. Using human skin cell assays as an initial model for snakebite-induced dermonecrosis, we show that the drugs 2,3-dimercapto-1-propanesulfonic acid (DMPS), marimastat, and varespladib, alone or in combination, inhibit the cytotoxicity of a broad range of medically important snake venoms. Thereafter, using preclinical mouse models of dermonecrosis, we demonstrate that the dual therapeutic combinations of DMPS or marimastat with varespladib significantly inhibit the dermonecrotic activity of geographically distinct and medically important snake venoms, even when the drug combinations are delivered one hour after envenoming. These findings strongly support the future translation of repurposed drug combinations as broad-spectrum therapeutics for preventing morbidity caused by snakebite.

Clinical Risk Factors Associated with Poor Outcomes in Snake Envenoming: A Narrative Review

Snakebite-related fatalities disproportionately affect populations in impoverished socio-economic regions, marked by limited access to adequate healthcare and constrained antivenom availability. Early medical intervention is pivotal in mitigating mortality and morbidity associated with snakebite envenoming (SBE). While clinical assessment remains fundamental in treating SBE, this review aims to spotlight objective parameters that could also affect outcomes. Selected studies that identify factors associated with poor outcomes are predominantly region-specific, single-site, and observational, yet collectively reveal similar findings. They consistently report factors such as treatment delays, susceptibility in vulnerable groups such as children and pregnant women, as well as various biochemical and haematological abnormalities. Acute kidney injury (AKI), low platelets, leucocytosis, abnormal coagulation, and elevated creatine kinase (CK) all show an association with poor outcomes. Furthermore, recognising rare and unusual SBE presentations such as adrenal insufficiency, severe hypertension, intracranial haemorrhage, acute angle closure glaucoma, and bowel ischaemia also has a bearing on outcomes. Despite the integration of these parameters into clinical decision tools and guidelines, the validation of this evidence is limited. This review underscores the imperative for high-quality, multi-centre studies aligned with consensus-driven Core Outcome Sets (COS) and Patient-Reported Outcome Measures (PROMS) to validate and strengthen the current evidence.